It is possible to power many sliding gate openers by solar power but simply some are easier and less expensive to convert than others. Indeed some have been designed with the very view that owners will want to power by solar.
Below is a kit that we have put together that allows a one click purchase for gates up to 300kg (motor is rated to 600kg).
After that you will find a list of other motors that work well with solar and links to solar kits and mounting posts.
SOLAR MOUNTING POSTS HERE
SLIDING GATE SOLAR POWERED KIT
Suitable for gates to 600kg.
The SOLARSLIDER kit comes complete with the following-
ID-400 Control board
Two remote controls
Enclosure for battery
25 watt solar panel